Python 求二叉树所有左叶节点的和

[woostundy]

python

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def sumOfLeftLeaves(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        if root is None or self.isleaf(root):
            return 0
        if self.isleaf(root.left):
            return root.left.val + self.sumOfLeftLeaves(root.right)
        else:
            return self.sumOfLeftLeaves(root.left) + self.sumOfLeftLeaves(root.right)
        
    def isleaf(self,root):
        return root.left is None and root.left is None

原题地址是 https://leetcode.com/problems/sum-of-left-leaves/ 求解，这段代码哪里写错了？

[billgreen1]

按我的理解， left leaves != left node

~~~python
def is_leaf(self, node):
return node is not None and node.left is None and node.right is None

[woostundy]

@billgreen1 是的，求的是所有左叶节点的和。
node is not None 的判断在最开始就做了。

错误样例是
[0,2,4,1,null,3,-1,5,1,null,6,null,8]
算这个的时候错了

[zmrenwu]

他不是要你算左叶子节点么？你的代码包含了非叶子节点在里面

[yonka]

return root.left is None and root.left is None

看了好几遍不知道在干嘛。
难道不是 return root is not None and root.left is None and root.right is None 吗？

[woostundy]

@yonka 我擦，看出来了，把第二个自判断也写成 left 了。。
晕，太马虎了

[woostundy]

@billgreen1 是我发现写错了。多谢多谢

[doraemon1293]

def isleaf(self,root):
return root.left is None and root.left is None 不应该是 right 吗